The invention relates to a method for mounting a rotor in a stator of an electrical machine, and to a mounting system for mounting such a rotor in a stator.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Electric motors, in particular, in synchronous-reluctance technology, are frequently subjected to vibrations and noise during operation due to asymmetries. Such vibrations and noise are generally disruptive for the intended use, but also for the operating personnel. Therefore, attempts have been made to reduce such vibrations and noise. However, not only electric motors, but in some circumstances, generators are also affected by asymmetries. Here, attempts have also been made to minimize corresponding vibrations and noise, if required.
The causes of these asymmetries firstly result from manufacturing inaccuracies. These include, for example, shape tolerances and positional tolerances of the stator laminations and rotor laminations. Further, inaccuracies may result generally from components such as the housing, stator, bearing shield, bearings and rotor of the electrical machine. In some circumstances, the inaccuracies accumulate, when the rotor is mounted in the stator.
Centering devices are generally used, when mounting a rotor in a stator. A radial fixing of the rotor relative to the stator is carried out thereby. The two components, housing and bearing shields, in this case generally have interference fits on the centering edges. This results in only one fixed position of the rotor relative to the stator.
Asymmetries may also result from the material itself. For example, the magnetic properties of magnetic steel sheet depend on the rolling direction. Significant force-related asymmetries may result, solely, from these minimal magnetic differences during operation of the electrical machine.
The material properties are typically not considered in an ideal alignment of the rotor axis. Motors in synchronous-reluctance technology are generally constructed with a smaller air gap than asynchronous motors. This is because, with a smaller air gap, there is a greater differentiation between the d-axis and q-axis, and also, the efficiency may be increased. At the same time, however, the susceptibility to vibrations, which originate in the electromagnetic system is increased.
It would therefore be desirable and advantageous to address prior art shortcomings and to provide improved rotor alignment in a stator by being able to consider asymmetrical magnetic forces.